/* Medium
Given a string IP, return "IPv4" if IP is a valid IPv4 address, "IPv6" if IP is a valid IPv6 address
or "Neither" if IP is not a correct IP of any type.

A valid IPv4 address is an IP in the form "x1.x2.x3.x4" where 0 <= xi <= 255 and xi cannot contain leading zeros.
For example, "192.168.1.1" and "192.168.1.0" are valid IPv4 addresses but "192.168.01.1",
while "192.168.1.00" and "192.168@1.1" are invalid IPv4 addresses.

A valid IPv6 address is an IP in the form "x1:x2:x3:x4:x5:x6:x7:x8" where:

1 <= xi.length <= 4
xi is a hexadecimal string which may contain digits, lower-case English letter ('a' to 'f')
and upper-case English letters ('A' to 'F').

Leading zeros are allowed in xi.
For example, "2001:0db8:85a3:0000:0000:8a2e:0370:7334" and "2001:db8:85a3:0:0:8A2E:0370:7334"
are valid IPv6 addresses, while "2001:0db8:85a3::8A2E:037j:7334"
and "02001:0db8:85a3:0000:0000:8a2e:0370:7334" are invalid IPv6 addresses.


Example 1:
Input: IP = "172.16.254.1"
Output: "IPv4"
Explanation: This is a valid IPv4 address, return "IPv4".

Example 2:
Input: IP = "2001:0db8:85a3:0:0:8A2E:0370:7334"
Output: "IPv6"
Explanation: This is a valid IPv6 address, return "IPv6".

Example 3:
Input: IP = "256.256.256.256"
Output: "Neither"
Explanation: This is neither a IPv4 address nor a IPv6 address.
Example 4:

Input: IP = "2001:0db8:85a3:0:0:8A2E:0370:7334:"
Output: "Neither"

Example 5:
Input: IP = "1e1.4.5.6"
Output: "Neither"

Constraints:
IP consists only of English letters, digits and the characters '.' and ':'. */

#include <string>

using namespace std;

class Solution {
public:
    string validIPAddress(string IP) {

    }
};